The research presented in this thesis has highlighted (bio)geochemical, hydrological, and wetland ecological processes that interact and enhance ecosystem development on wetlands built on fine sediment. A combination of greenhouse and laboratory experiments were conducted. Some measured data from these experiments formed important input for subsequent analysis in a modeling environment. The findings presented in Chapters 2-6 can be divided into four topics: 1) Plant–soil interactions in the terrestrial zone, 2) wetland–terrestrial processes influencing nutrient availability in the land–water zone, 3) effects of plants on sediment consolidation in the terrestrial zone, and 4) effects of bioturbation on nutrient availability in the aquatic zone. The next sections give a summary of the results for these four topics. The last section summarizes the recommendations formulated for the Marker Wadden project.
MULTIFILE
The world population is ageing rapidly. As society ages, the incidence of physical limitations is dramatically increasing, which reduces the quality of life and increases healthcare expenditures. In western society, ~30% of the population over 55 years is confronted with moderate or severe physical limitations. These physical limitations increase the risk of falls, institutionalization, co-morbidity, and premature death. An important cause of physical limitations is the age-related loss of skeletal muscle mass, also referred to as sarcopenia. Emerging evidence, however, clearly shows that the decline in skeletal muscle mass is not the sole contributor to the decline in physical performance. For instance, the loss of muscle strength is also a strong contributor to reduced physical performance in the elderly. In addition, there is ample data to suggest that motor coordination, excitation-contraction coupling, skeletal integrity, and other factors related to the nervous, muscular, and skeletal systems are critically important for physical performance in the elderly. To better understand the loss of skeletal muscle performance with ageing, we aim to provide a broad overview on the underlying mechanisms associated with elderly skeletal muscle performance. We start with a system level discussion and continue with a discussion on the influence of lifestyle, biological, and psychosocial factors on elderly skeletal muscle performance. Developing a broad understanding of the many factors affecting elderly skeletal muscle performance has major implications for scientists, clinicians, and health professionals who are developing therapeutic interventions aiming to enhance muscle function and/or prevent mobility and physical limitations and, as such, support healthy ageing.
Background: Malnutrition is an important cause of the excessive morbidity and mortality rate of dialysis patients. Frequent nocturnal home hemodialysis (NHHD) has many benefits compared with conventional thrice-weekly hemodialysis (CHD), due to the virtual absence of dietary restrictions and a much higher overall dialysis efficiency. In this observational study, we investigated whether these benefits of NHHD translate into an improved nutritional intake, with a special emphasis on protein intake. Methods: We prospectively assessed the effect of the transition of CHD to NHHD on nutritional intake (5-day dietary intake journal), normalized protein catabolic rate, and anthropometric parameters in 15 consecutive patients who started NHHD in our center between 2004 and 2009 and completed at least 8 months of follow-up. Data were collected before the transition from CHD to NHHD and 4 and 8 months after the transition. Results: Protein intake, as measured by both dietary intake journal and normalized protein catabolic rate, increased significantly after the transition from CHD to NHHD. Accordingly, phosphate intake increased significantly; however, serum phosphate levels did not increase, despite negligible phosphate binder use during NHHD. Body mass index and upper arm muscle circumference did not change significantly. Conclusion: The transition from CHD to NHHD has a positive effect on nutritional intake, in particular, protein intake. NHHD should be considered in malnourished patients on CHD. © 2012 National Kidney Foundation, Inc.
